The present invention relates to water treatment systems and, in particular, to a multi-stage, disposable cartridge filter including a housing having liquid impermeable sidewalls and usable with a manifold mounted residential water supply system.
Varieties of filtration systems have been developed for multi-user, residential water supplies serviced by a community water provider or personal on-sight well. Such systems typically include a manifold assembly that mounts to the supply conduits which supply the dwelling. The manifold assembly, in turn, typically includes a threaded headpiece that is secured to the supply conduits and a detachable cover that is secured to the headpiece to contain a filtration media. Some of these systems mount adjacent to a sink such as the kitchen sink in many homes.
Some systems provide a manifold cover which contains a renewable, loosely packed granulated filtration media. Other systems provide disposable cartridges having porous support assemblies such as pre-formed screens, which segregate the granular media and direct liquid flow through the media. Liquid flow is directed in most of such systems in a linear or end-to-end fashion through one or more sequentially arranged zones of media to remove predetermined contaminants. Some systems may provide linear serpentine flow paths within the cartridge. Examples of some of such systems can be found upon directing attention to U.S. Pat. Nos. 3,152,077; 3,342,340; 3,705,651; 4,626,350; 4,659,467; 4,731,183; 4,769,143; 4,913,808; and 4,948,505.
Difficulties can arise from such linear flow filters through an inefficient use of the media. That is, blockages or normal sediment collection at the upstream side of the filter increases system back pressure and can lead to premature disposal of the media before it is fully spent. Other difficulties arise from uneven packing of the granular media which leads to a non-uniform filtration porosity over the length of the media and which discourages a radial flow arrangement. Poured media beds also do not provide a sufficiently small porosity to filter many small particles or molecular contaminants, such as many heavy metals, agricultural chemicals and the like. Most typically, poured beds are capable of a filtration porosity of not less than 400 microns.
Some manifold systems exist which provide radial flow characteristics. Examples of two of such systems can be found at U.S. Pat. Nos. 3,262,570 and 3,289,847 and wherein unsealed, exposed filter media assemblies are provided. That is, the filter media cartridges do not provide surrounding liquid impermeable housings which contain and protect the media. In particular, the 3,262,570 cartridge provides an exposed, full length fiber media which concentrically surrounds an impermeable tube that contains a single bed of granular particulate. Radial flow occurs only between the fiber media and housing. The 3,289,847 cartridge, provides a cloth wrapped screen cartridge and two concentric cavities that contain granular media and provide radial flow to a center bore.
U.S. Pat. No. 5,024,764 discloses an exposed, cloth wrapped media which contains a single core of an annular cast block of powdered carbon material.
Although providing advantages of radial flow, difficulties can arise with the foregoing media through normal handling and shipping. That is, normal handling can damage or deform the media support structure, induce leakage of the media or cause a fracturing of the cast media.
Applicant is also familiar with a variety of sealed filtration assemblies, wherein the media is contained in a liquid impermeable housing, which directly attach to faucet-type water supplies. Liquid flow is directed in these assemblies along linear flow paths and sequentially arranged treatment stages. In some assemblies the flow paths may wind back and forth in a serpentine arrangement between inlet and outlet ports. Some of these assemblies are shown at U.S. Pat. Nos. 4,824,565; 4,711,723; 4,561,976; 3,529,726; 3,342,340; 1,774,004; 1,287,755; and 325,681.
In contrast to the known art, the present invention provides a novel radial flow filtration cartridge and disposable manifold assembly wherein a liquid impermeable housing contains several stages of filtration media. Each of the stages is arranged to obtain radial flow from an outer cavity space to a center outlet bore and preferably provides an annularly cast block of media of uniform porosity. Each stage also exhibits a preferred filtration characteristic that can be tailored to the application. In addition to removing sediment, odors and materials which affect taste, the filter media is selected and configured to advantageously filter suspended heavy metals, such as lead, and varieties of so-called "VOC" or volatile organic contaminants, herbicides, pesticides, bacteria, parasites, and industrial and agricultural chemicals.